Optical fiber cables have been deployed extensively for long-haul trunking installations. Optical fiber cables used for these installations are typically high fiber count cables containing up to approximately one hundred fifty individual optical fibers with each fiber carrying high density, high data rate transmissions.
Optical fiber cables are now being used for local loop applications and are anticipated to be the media of choice for communications service to homes and businesses. As optical fiber cables are used more extensively in telecommunications service to homes and businesses, cable fiber counts are expected to increase. Optical fiber cables with fiber counts as high as five hundred are expected in the future.
One feature of high fiber count cables that must be addressed, however, is the organization of the individual fibers within the cable. Cable sheath size, splicing efficiency, and fiber mechanical integrity and optical performance are all influenced by cable designs necessary for a particular fiber count. During an optical fiber cabling operation, the optical fibers are typically divided into identifiable, longitudinally extending fiber units. A fiber unit is formed by any one of several methods. One method of forming a fiber unit is by wrapping a plastic color-coded roving material helically about a predetermined group of fibers. Another method is to extrude a solid, color-coded plastic tube about a group of fibers. Still another method is to create a ribbon fiber unit wherein a chosen group fibers, for example twelve fibers, are arranged in a planar array which is held together between two opposing adhesive backed plastic binding tapes as described in Eichenbaum et al., U.S. Pat. No. 4,289,558 issued Sept. 15, 1981. In the alternative, the array may be held together by extruding a polymeric bonding material into a nip formed between each pair of parallel fibers in contact with each other.
Transmitting and receiving electro-optic devices are connected to the ends of optical fiber cables and, in so doing, communications links are provided. The connection of these electro-optic devices as well as the concatenation of optical fiber cables may be effected by any of a number of methods. For example, a cabled fiber end may be spliced to an optical fiber pigtail attached to an electro-optic device by a process referred to as fusion splicing wherein two fiber ends are precision cleaved, held in close proximity and welded together by an electric or ignited gas arc. Fusion splicing may also be used to concatenate fibers of two or more optical cables.
Splicing may also be accomplished by the use of an index matching adhesive to bond fiber ends face to face. A rigid ferrule device is typically employed to maintain the alignment and mechanical integrity of the splice. Also, mating mechanical connectors may be adapted to ends of two fibers to be spliced and caused to be brought into engagement with one another as described in U.S. Pat. No. 4,793,683 which issued on Dec. 7, 1988 in the names of T. C. Cannon, Jr., B. V. Darden and N. R. Lampert.
Pluralities of optical fibers may be joined by utilizing a multifiber splicing device such as an AT&T array connector, for example, described in U.S. Pat. No. 3,864,018 which issued on Oct. 18, 1973 in the name of C. M. Miller. Use of the array connector allows the splicing of a plurality of fibers in a single operation. This method is particularly useful for the splicing of optical cables which include the ribbon fiber units described above.
During the process of applying array connectors to fiber ribbon units, the ribbon binding tapes are peeled from the ribbon fiber unit, exposing end portions of the optical fibers. The optical fiber end portions are stripped, cleaned and cleaved and then positioned in the grooves of a first one of two array chips in such a manner that the fiber end portions extend slightly past an end of the first chip. A second array chip which is also provided with a plurality of grooves is placed over the first array chip having the fiber end portions positioned therein. A curable adhesive is applied to the fibers in the location of the chips and this assembly, referred to as an array connector, is clamped and allowed to cure. After the adhesive is cured, the slightly extending fiber end portions are ground flush with the face of the chip assembly and the array connector assembly is complete.
Array connectors may be used with cables which do not include ribbon fiber units. It is possible to assemble unbound fibers with the array chips to effect connectorization, however, it is preferable first to bind the optical fibers extending from a cable sheath into ribbons and then proceed with the application of the array chips to form the array connector. In this way, an organized fiber ribbon extends from the array connector instead of a plurality of unbound fibers. This is advantageous because in the ribbon format, the entire ribbon acts as a strength member for each fiber of the ribbon. The risk of fiber breakage during array connector fabrication and cable use is therefore reduced when the ribbon format is used with the array connector.
Because slight variations in the structure of the ribbon can affect significantly the cable's optical performance, uniformity and reproducibility of the ribboning process is essential to the successful ribboning of the fibers of a loose fiber cable. Heretofore in the prior art, the ribbon making process was performed manually. High quality fabricated ribbons result from this prior art method; however, the time required to fabricate the ribbon is excessive. What is needed and what seemingly is nowhere shown in the prior art are apparatus and methods for at least a semi-automated ribbon fabrication of optical fibers of previously cabled optical fibers which are in non-ribbon form.